1. Field of the Invention
The present invention relates to a control device for a hybrid vehicle having an engine and a motor for outputting driving power, and in particular, the present invention relates to a control technique which controls the amount of regeneration during regenerative operation of the motor when the vehicle decelerates.
2. Description of the Related Art
A traction control device for a four-wheel drive hybrid vehicle, such as a traction control device for a four-wheel drive hybrid vehicle disclosed in Japanese Unexamined Patent Application, First Publication No. Hei 09-284911, in which the hybrid vehicle comprises an internal combustion engine and a first motor for driving one of front wheels or rear wheels, and a second motor for driving the other of the front wheels or rear wheels, and which controls traction distribution based on the state of charge of a battery device which communicates with each of the motors in terms of electrical energy, has been known in the art.
The above traction control device comprises a traction distribution control section which, when one or more wheels is slipping (i.e., slip state), controls traction distribution to the front and rear wheels so as to stop slipping of the wheels, and a distribution change restriction section for restricting change in traction distribution to the front and rear wheels when the vehicle turns, and thus the control device is constructed so as to ensure the maneuverability and stability of the vehicle while ensuring desired traction.
For example, the traction distribution control section in a slip state is constructed so as to set the vehicle to be in a four-wheel drive mode and also to reduce only the traction of the slipping wheels so as to stop the slipping of the wheels when slipping is detected based on a difference between the rotational speeds of the front wheels and rear wheels which are measured using wheel speed sensors.
Moreover, the distribution change restriction section is constructed so as to prohibit the change in the drive mode other than a predetermined drive mode change based on the determination as to whether the maneuverability and stability of the vehicle may be lost by the change in the drive mode when the vehicle turns.
In the above-mentioned conventional control device for a four-wheel drive hybrid vehicle, a problem occurs in that the total amount of regenerated energy which can be recovered in the entire vehicle is reduced if merely the regenerative torque of the slipping wheel is reduced, or if merely the regenerative operation of the slipping wheel is prohibited as in a state in which the vehicle is driven, when, for example, the vehicle is in a state in which the first and second motors are used in regenerative operation mode.